Electric circuit breaker



Nov. 19, 1940. M, FREEMAN ETAL 2,222,291

ELEGTRI C CIRCUIT BREAKER Filed 001;. 19, 1938 INVENTORS CHARLES RAGOV/N AND BY MAURICE FREEMAN A TTORNEY.

Patented Nov. 19, 1940 UNITED STATES 2,222,291 4 ELECTRIC omcurr BREAKER Maurice Freeman and Charles Ragovin,

- Brooklyn, N. Y.

Application October 19, 1938, Serial No. 235,767

Claims.

This invention'relates generally to electric circuit breakers, and particularly to a circuit breaker designed to replace a cartridge type fuse.

The primary object of the present invention is to provide a cartridge type circuit breaker which is of simple and inexpensive construction, and may be assembled at relatively low cost.-

Anotherobject is to provide an efficient cir= cuit breaking structure whose electrically conducting elements require no solder at their junctions, and which will operate to protect electri cal systems against overloads and short circuits.

A further object is to provide a cheap and practical cartridge type circuit breaker which employs a bi-metallic thermal element respon sive to an increase in current above the rated amount as determined by the dimensions oi the element, to open the circuit.

Other objects and .features of the invention will appear from a reading of the following description which is accompanied by a drawing,

wherein: I

Fig. 1 shows, in perspective, a cartridge type circuit breaker of the invention as it appears completely assembled;

Fig. 2 is a crossesection of the circuit breaker of Fig. l;

Fig. 3 is an exploded view of the individual parts of the circuit breaker of Figs. 1 and 2; and

Fig. i is a perspective view of the insulating tubular member with the thermal element mounted thereon, before the terminal caps are placed in position to complete the assemblage.

In the drawing the same reference numerals represent the same parts throughout the figures.

The cartridge type circuit breaker of the invention comprises a central tubular n'iemberv of suitable insulating material, suchas fibre, supporting at one end a bi-metallic thermal element 2 located in its interior, and a pair of hollow metallic terminal caps or'heads E, 3 in contact with the ends .of the thermal element. Thermal element 2 is constructed from two closely united metals of different temperature coefficients of expansion, so as to expand upon a flow of current therethrough which exceeds a rated amount. One end 4 of the thermal element is curved into the form of a ,U so as to hook upon the supporting end 6 of the insulating member]. The other end 5 of element .2 is free and is bent at right angles to its longitudinal dimension so as to make contact with one of the terminal caps 3. v

In order to support the thermal unit 2 at its curved end, a portion of the tubular insulating member i is cut away at end 8 in a beveled or wedge-shaped fashion, as shown. The other end i of the tubular insulating member I is provided with an aperture or slot to permit the free end i of the thermal unit to protrude there- 5 through when making contact with its associated cap it, and to move away from the cap to assume the position indicated in dotted lines in Fig. 2, in order to break the circuit upon the occurrence of an overload or short circuit. 10

The thermal element 2, when mounted on tubular member l in its interior, as indicated in Figs. 2 and i, is substantially parallel to the axis of the insulating body, and, if desired, may be bent slightly to give it a'certain tension to insure that the free end 5 will make contact with its associated terminal cap. Should the flow of current through the thermal element exceed the rated amount, as determined by the dimensions of the element, the metal thereof will ex- 39 pand in a direction to cause the free end 5 to withdraw from the aperture ll into the interior of the tubular insulating member, thus breaking the circuit.

it should be noted that the end i of tubular member 3 extends slightly beyond the free end 5 of the thermal unit. This is to insure that the free end of the thermal element does not engage the cap when it expands into the insulating tube.

One advantage of the circuit breaker of th present invention is that it requires no solder joints between the'metallic terminal caps 3, 3 and the thermal element 2, thus making it inexpensive to manufacture. The caps 3, 3 merely slide over the ends or the tubular member 5 and make frictional contact with the ends of the thermal element 2. Of course, the curved end d of the thermal element is sumciently raised above the Wedge-shaped cut to insure good contact with its associated terminal cap. If desired, the caps 3, 3 may becrimped after they have been assembled on the tubular memher, as shown at 3, to insure a tight fit on the cartridge. I The circuit breaker oi the invention may be used over a lon period of time, permitting reclosure or the circuit, after indicating an overload'o-r short circuit, without requiring replacement of the thermal element. The invention has been used with good re sults to replace an automobile cartridge fuse, and may be used either with low or highvoltage systems.

It is to be expressly understood, however, that v the flguresof the drawing are for the purpose said thermal element, whereby when said circuit of illustration only, and are not to be construed as a definition of the limits of the invention.

reference being had for this purpose to the appended claims.

What is claimed is: 1. An automatic circuit breaker comprising a nonconducting housing having a pair of spaced apertures in the length thereof, a thermal elefree end thereof to withdraw into said housing to break contact with its associated terminal.

2. An automatic circuit breaker comprising a nonconducting housing having at one end a wedge-shaped cut and at the other end an aperture, a thermal element within said housing,

said element having one end thereof curved over said wedge-shaped cut-for support by said housing, the other end of said element being free and normally protruding through said aperture, and spaced, metallic terminals placed over the ends of said-housing for engaging the ends oi breaker is subjected to an overload of current, said thermal element becomes heated and expands in such direction as to cause the free end thereof to withdraw into said housing to break contact with its associated terminal.

3. An electric circuit breaker comprising a tubular insulating body supporting at one end thereof a thermal element which will become heated and expand upon the passage of current therethrough exceeding a rated amount, said element being disposed in the interior of said body, the free end of said thermal 'element being located within the length of said tubular body and bent at a substantial angle to its lon gitudinal dimension so as to normally protrude through an aperture in said body, and hollow,

ends of said insulating body for making contact with the ends of said thermal element, said element being adapted to expand upon an over- .load of current to cause its free end to retract within said insulating body, whereby contact with one of said caps is broken.

4. A cartridge type electric circuit breaker comprising a tubular insulating body supporting at one end thereof a thermal element which will become heated and expand upon the passage of current therethrough exceeding a rated amount, said element being disposed in the interior of said body and having its longitudinal dimension substantially parallel to the axis thereor, the free end of said thermal element being located within the length of said tubular body and bent at a substantial angle to its longitudinal dimension so as to normally protrude through an aperture in said body, and hollow, spaced, metallic terminal caps placed over the ends of said insulating body for making contact with the ends of said thermal element, said element being adapted to expand upon an overload of current to cause its free end to retract within said insulating body, whereby contact with one of said caps is broken.

5. A cartridge type electric circuit breakercomprisinga substantially cylindrical tubular insulating body supporting at one end thereof a bimetallic thermal element which will become heated and expand upon the passage of current therethrough exceeding a rated amount, said element being disposed in the interior of said body and having its longitudinal dimension substantially parallel to the axis thereof, the free end of said thermal element being located within the length of said tubular body and bent substantially perpendicular to its longitudinal dimension so as to normally protrude through an aperture in said body, and hollow, spaced, metallic terminalcaps slidable over the ends of said insulating body for making contact with the ends of said thermal element, said caps being crimped to insure a tight fit on said insulating body, said element being adapted to expand upon an overload of current to cause its free end to retract within said insulating body, whereby contact with one of said caps is broken.

- MAURICE FREEMAN.

CHARLES RAGOVIN. 

